JPH07331123A - Aqueous dispersion resin composition for rust preventive coating - Google Patents

Abstract

PURPOSE:To obtain an aqueous dispersion resin composition excellent in rustproofness, water resistance and adhesion to metal by dispersing a polymer containing a specified (meth)acrylate monomer in water. CONSTITUTION:This composition comprises an aqueous dispersion of a polymer containing at least 0.1wt.% monomer of the formula (wherein R is H or methyl; A and B are each optionally substituted 1-10C alkyl; and m and n are each 0 to 100). Examples of the monomer to be used include benzyl acrylate (of formula II) and phenoxyethyl methacrylate (of formula III). The amount of the monomer of formula I to be used is at least 0.1wt.%, preferably 1-80wt.%, based on the total monomer mixture. It is most effective to produce the composition by emulsion polymerization which requires no organic solvent. However, for only the adhesiveness of the coating film, even the composition obtained by the solution polymerization of the monomers in a hydrophilic solvent and adding water thereto to form an aqueous dispersion or solution can exhibit the same effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-dispersible resin composition for water-based rust-preventive coating which is newly useful. More specifically, the present invention relates to a water-dispersible resin composition for a water-based rust preventive coating, which has excellent rust resistance, water resistance, and adhesion (adhesion) to metal.

[0002]

2. Description of the Related Art Conventionally, as an anticorrosive paint primer for steel frames, etc., alkyd resin consisting of long oil, medium oil, etc. has been used for toluene,
Alkyd phthalate paints diluted with a mixed solvent such as xylene have been widely used.

However, due to recent social problems related to air pollution caused by organic solvents, and regulatory measures related to transportation and storage due to revision of the Fire Service Act of May 1990,
It has been desired to develop an anticorrosive paint that is water-based and has no environmental pollution. Therefore, the problems to be solved including the adverse effects on the human body caused by the organic solvent-based paint are obvious.

By the way, as one of the measures for making the rust-preventive paint non-polluting, the use of a water-dispersible resin composition containing water as a medium is toxic by the solvent of the organic solvent-based paint, air pollution, and fire caused by ignition. It is effective for some problems to be solved such as explosion. However, water-dispersible resin-based paints that use water as a medium are more suitable than non-aqueous paints that use organic solvents as a medium in terms of rust prevention, adhesion to metals, etc. when the metal surface is the object to be coated. And its ability is insufficient.

Generally, the anticorrosive property of a coating film is due to the adhesion of the coating film to a metal, water resistance, and the denseness that does not allow water vapor to pass through. Usually, the coating film is adhered by a hydrogen bond between a functional group and a metal, such as a carboxylic acid or a hydroxyl group of a polymer constituting the coating film, and the coating film is improved in water resistance and denseness by crosslinking or hydrophobization. As for the adhesiveness, as long as the metal and the film-constituting molecule do not chemically bond with each other, hydrogen bonding alone loses its effect when water is present on the bonding surface. For example, in a film obtained from an ordinary water-based emulsion-polymerized resin composition, due to the film formation form and the presence of a hydrophilic portion, perfect water resistance such that even a trace amount of water does not reach the interface between the coating film and the metal substrate, Denseness was impossible, and it was difficult to rely on the adhesiveness due to hydrogen bonding.

However, due to social and practical reasons, there has been a great demand for the development of a pollution-free rust-preventive paint which does not use an organic solvent and has excellent adhesion to a metal surface.

[0007]

DISCLOSURE OF THE INVENTION The present invention replaces an organic solvent-based paint, which is usually used as an anticorrosion paint, with problems such as environmental pollution, solvent poisoning, and fire, with a water-free medium as a medium. It is a water-dispersible resin composition coating with excellent safety, pollution-free rust resistance and water resistance, and rust prevention with improved adhesion between coating film and metal, which is the biggest problem of water-based resin coatings. The purpose is to develop a resin composition that can be used in paints.

[0008]

The present invention is based on the general formula (1)

[Chemical 2] [Wherein R is a hydrogen atom or a methyl group, A and B are alkyl groups having 1 to 10 carbon atoms which may have a substituent, m
And n represent a number from 0 to 100. ] A water-dispersible resin composition for rust-preventive coatings, which is a water-dispersible composition of a polymer containing at least 0.1% by weight of the monomer represented by the above formula, and monomers 1-80 represented by the general formula (1). %, And one or more copolymerizable monomers of at least styrene and (meth) acrylic acid alkyl ester monomers 99
To 20 wt% mixed monomer 100 parts by weight, surfactant 0.001 to 5 parts by weight, water 30 to 80 parts by weight and emulsion polymerization together with a water-soluble polymerization initiator. The above object was achieved by developing a method for producing a water-dispersible resin composition.

The present invention will be described in more detail below. Examples of the monomer represented by the general formula (1) usable in the present invention include benzyl acrylate,

[Chemical 3] Vedizyl methacrylate,

[Chemical 4] Phenoxyethyl acrylate,

[Chemical 5] Phenoxyethyl methacrylate,

[Chemical 6] Phenoxydiethylene glycol acrylate,

[Chemical 7] Phenoxydiethylene glycol methacrylate,

[Chemical 8] 2-hydroxy-3-phenoxypropyl acrylate,

[Chemical 9] 2-hydroxy-3-phenoxypropyl methacrylate,

[Chemical 10]

The amount of the monomer represented by the general formula (1) used is at least 0.1% by weight, preferably 1 to 80% by weight, more preferably 2 to 50% by weight, based on the total mixed monomers. . All the mixed monomers may be monomers represented by the general formula (1). If the amount of the monomer represented by the general formula (1) is less than 0.1% by weight in the total mixed monomer, the effect of the present invention cannot be obtained.

The present invention also includes a monomer represented by the general formula (1) and a copolymerizable monomer comprising at least one of styrene and a (meth) acrylic acid alkyl ester copolymerizable with the monomer (hereinafter, A copolymerizable monomer) may be used. As typical examples of the copolymerizable monomer, for example, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, (meth)
Acrylic acid-n-butyl, isomethacrylic acid isobutyl, (meth) acrylic acid-tert-butyl, (meth)
Similarly, 2-ethylhexyl acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, cyclohexyl (meth) acrylate, or a mixture of these copolymerizable monomers can be used.

In addition to the copolymerizable monomers listed above,
To improve stability such as storage stability of the obtained emulsion copolymer, to crosslink within particles or between particles to increase cohesive force of the resin film, or to improve adhesion to metal. Further copolymerizable (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, glycidyl (meth) acrylate, glycidyl crotonate, glycidyl allyl ether, (meth) acrylamide, N-methylol An unsaturated monomer such as (meth) acrylamide, α-methylstyrene, (meth) acrylonitrile, vinylidene chloride, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate is used as the copolymerizable monomer. In addition to the above, it can be used as a mixture containing one or more kinds.

The copolymerizable monomer may not be used, but when used, the amount of the copolymerizable monomer used is at most 99.9% by weight of the total mixed monomers. Below, preferably 99 to 20% by weight, more preferably 98 to 50
% By weight.

In order to crosslink or increase the molecular weight of the resulting copolymer, if necessary, an unsaturated bond such as divinylbenzene, ethylene glycol di (meth) acrylate or glycerin tri (meth) acrylate may be incorporated into one molecule. A crosslinkable monomer having two or more of these can be used in combination. The crosslinkable monomer is 10% by weight in the total mixed monomer.
It is preferably used in the following amounts.

Further, as the surfactant for emulsion polymerization,
Well-known and commonly used surfactants that are generally used conventionally are used. Preferably, a reactive surfactant, for example, Aqualon HS-10, H-3330PL (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adecaria Soap SE-10N (manufactured by Asahi Denka Co., Ltd.), Latemur S-180A (Kao). (stock)
), Eleminol JS-2, Eleminol RS-30
(Manufactured by Sanyo Chemical Industry Co., Ltd.) and other polymers (oligomers)
It is preferable to use a system emulsifier because it does not impair the water resistance of the film. In the case of emulsion polymerization, it is necessary to add the surfactant in an amount of 0.001 part by weight or more based on 100 parts by weight of the mixed monomer. Although a large amount of the surfactant does not affect the emulsion polymerization reaction, the coating film obtained will increase the hydrophilicity, so if the upper limit is determined by force, it will be 5
It is preferable to use less than or equal to parts by weight.

The amount of water used for emulsion-polymerizing the mixed monomer is 30 to 80 parts by weight, preferably 40 to 70 parts by weight, based on 100 parts by weight of the mixed monomer. If the amount of water used is less than 30 parts by weight, the polymerization is difficult, and if it exceeds 80 parts by weight, the solid content is small and the viscosity is low, which is not practical.

As the polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide solution, peroxides such as benzoyl peroxide and tert-butyl hydroperoxide, and azobisisobutylnitrile are generally used. However, a water-soluble polymerization initiator and a water-soluble redox type polymerization initiator system are particularly preferable. The amount of the water-soluble polymerization initiator used is preferably 0.001 to 0.01 part by weight, based on 100 parts by weight of the total mixed monomer.

Furthermore, in order to adjust and adjust the molecular weight of the emulsion copolymer, various known chain transfer agents such as alcohols (catechols) and thiols may be used. Emulsion polymerization is performed by a usual method. The polymerization temperature is preferably in the range of 30 to 90 ° C.

As described above, the water-dispersible resin composition of the present invention contains the monomer represented by the general formula (1) as an essential component in an amount of 0.1 to 100% by weight of the total mixed monomers, preferably Is a water-dispersible resin composition for a water-based anticorrosive coating containing 1 to 80% by weight, and more preferably 2 to 50% by weight, but if necessary, a plasticizer, a film-forming assistant, a dispersant, a surface conditioner, Well-known and commonly used additives such as antiseptics, defoaming agents and anticorrosives can be appropriately selected and added as long as the object of the present invention is not impaired. If it is a colored paint, it should be mixed with a pigment, and if it is a clear film, it should be used without a pigment.

[0020]

The water-dispersible resin composition of the present invention is excellent in rust resistance, water resistance and adhesion to metal. The reason why the excellent physical properties of the water-dispersible resin composition of the present invention are expressed is presumed as follows.

That is, the rust preventive property is due to the adhesion of the coating film to the metal, the water resistance, and the denseness that does not allow the permeation of water vapor. Usually, the coating film is adhered to the metal by hydrogen bonding, and cross-linking or hydrophobicity is performed. Although water resistance and denseness are improved by the addition of water, the effect cannot be exhibited due to the presence of water only by hydrogen bonding. In the emulsion polymerized resin film, perfect water resistance and denseness that prevent water from reaching the film formation interface were extremely difficult due to the film formation form and the presence of hydrophilic portions.

However, in the polymer containing the monomer represented by the general formula (1) used in the present invention, the side chain has a benzene ring which is relatively free to move, and the plane of the benzene ring is a plane. By adhering the structure to the metal surface, the adhesion to the metal surface can be improved, and unlike hydrogen bonding, the adhesion is not hindered by the presence of water. Can be obtained.

The water-dispersible resin composition of the present invention is most effectively produced by emulsion polymerization which does not require an organic solvent, but if only the adhesion of the coating film is intended, a hydrophilic solvent is used. The same effect can be exhibited even with a resin composition in which solution polymerization is performed therein and then water is added to make the solution water-soluble and / or water-soluble.

[0024]

EXAMPLES Next, the present invention will be described more specifically by way of Examples and Comparative Examples. In the following, all parts and% are based on weight unless otherwise specified.

To 100 parts of each of the water-dispersible resin compositions obtained in the examples and comparative examples, 10 parts of texanol (film forming aid) was added, and this was applied to a degreased cold-rolled steel sheet (bright finish). Use a film applicator to coat to a dry film thickness of 30 μm, then 2
After drying at 0 ° C., 65% RH for 24 hours, various tests were conducted.

Test Conditions The rust resistance was evaluated by a salt spray resistance test according to JIS K-5400, and the adhesion to metal was JIS K-540.
It was evaluated by a cross-cut test according to 0. Water resistance is 168 after tapping the side and back of the test piece into tap water at 20 ° C.
After soaking for a period of time, a cross-cut test according to JIS K-5400 was carried out, and the water-resistant adhesion was evaluated.

(Example 1) 1. A reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged with a surfactant (Adecaria Soap SE-10N, manufactured by Asahi Denka Kogyo Co., Ltd.).
Add 0 parts and 200.0 parts of water and raise the temperature to 75 ° C. On the other hand, in 20 parts of water, a surfactant (Adecaria Soap S
E-10N (Asahi Denka Kogyo KK) 3.0 parts was added and dissolved, and 250.0 parts of styrene, 2-ethylhexyl acrylate 100.0 and benzyl acrylate 5 were added thereto.
Add 0.0 parts of mixed monomer and stir well to emulsify, put in a dropping funnel, put 5% of this monomer emulsion into a reaction vessel, and add 0.5 part of an excess as a polymerization initiator. After potassium sulfate was added and the temperature was raised to 80 ° C. and held for 10 minutes, the remaining monomer emulsion and 50.0 parts of a 3% potassium persulfate aqueous solution were uniformly added dropwise over 3 hours. After the dropwise addition was completed, an aging reaction was performed at 80 ° C. for 1 hour and then cooled to room temperature to obtain a water-dispersible resin composition.

(Example 2) 245.0 parts of styrene, 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that a mixed monomer of ethylhexyl acrylate 95.0, benzyl acrylate 50.0 parts and methacrylic acid 10.0 parts was used as a monomer emulsion. Finally, 3 parts of ammonia water was added for neutralization to obtain a water-dispersible resin composition.

Example 3 A surfactant (H- was added to a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel.
3330PL Daiichi Kogyo Seiyaku Co., Ltd. 30.0 parts and water 200.0 parts are put and temperature is raised to 75 degreeC. On the other hand, 20.0 parts of a surfactant (H-3330PL Daiichi Kogyo Seiyaku Co., Ltd.) was added to and dissolved in 20 parts of water, and 250.0 parts of styrene and 10 parts of 2-ethylhexyl acrylate were dissolved therein.
A mixed monomer of 0.0 and 50.0 parts of benzyl acrylate was added and stirred, and after well emulsified, this was placed in a dropping funnel, and 5% of this monomer emulsion was charged into a reaction vessel to prepare a polymerization initiator. As a result, 0.5 part of potassium persulfate is added and the temperature is raised to 80 ° C. and held for 10 minutes, and then the remaining monomer emulsion and 50.0 parts of a 3% potassium persulfate aqueous solution are homogenized over 3 hours. Dropped. After the dropwise addition was completed, an aging reaction was performed at 80 ° C. for 1 hour and then cooled to room temperature to obtain a water-dispersible resin composition.

(Example 4) 225.0 parts of styrene and 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that the monomer mixture was 75.0 parts of ethylhexyl acrylate and 100.0 parts of benzyl acrylate, and a water-dispersible resin composition was obtained. It was

(Example 5) 250.0 parts of styrene and 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that a mixed monomer of 100.0 parts of ethylhexyl acrylate and 50.0 parts of benzyl methacrylate was used as a monomer emulsion to obtain a water-dispersible resin composition. It was

Example 6 250.0 parts of styrene and 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that a mixed monomer of 100.0 parts of ethylhexyl acrylate and 50.0 parts of phenoxyethyl acrylate was used as a monomer emulsion to obtain a water-dispersible resin composition. Obtained.

Example 7 250.0 parts of styrene and 2-
100.0 parts of ethylhexyl acrylate and 50. 2-hydroxy-3-phenoxypropyl acrylate.
Emulsion polymerization was carried out in the same manner as in Example 1 except that 0 part of the mixed monomer was changed to a monomer emulsion to obtain a water-dispersible resin composition.

(Example 8) Emulsion polymerization was carried out in the same manner as in Example 1 except that 400 parts of benzyl methacrylate was used as a monomer to obtain a water-dispersible resin composition.

(Example 9) 267.0 parts of styrene and 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that a mixed monomer of 117.0 parts of ethylhexyl acrylate and 16.0 parts of benzyl acrylate was used as a monomer emulsion to obtain a water-dispersible resin composition. It was

(Comparative Example 1) 275.0 parts of styrene, 2
Emulsion polymerization was carried out in the same manner as in Example 1 except that 125.0 parts of -ethylhexyl acrylate was used as a monomer emulsion to obtain a water-dispersible resin composition.

(Comparative Example 2) 270.0 parts of styrene, 2
-Emulsion polymerization was carried out in the same manner as in Example 1 except that the monomer emulsion was a mixed monomer of 120.0 parts of ethylhexyl acrylate and 10.0 parts of methacrylic acid, and a water-dispersible resin composition. Got

(Comparative Example 3) 275.0 parts of styrene, 2
Emulsion polymerization was carried out in the same manner as in Example 3 except that a mixed monomer of 125.0 parts of -ethylhexyl acrylate was used as a monomer emulsion to obtain a water-dispersible resin composition.

The composition of the monomers for the respective water-dispersible resin compositions obtained in each of the above Examples and Comparative Examples and the prevention of the water-dispersible resin compositions obtained in each of the Examples and Comparative Examples. Table 1 shows a summary of comparative examinations of rust resistance, adhesion to metal, and water resistance.

[0040]

[Table 1]

As is clear from Table 1, the water-dispersible resin composition for rust preventive coating of the present invention is excellent in rust preventive property, water resistance and adhesion to metal.

[0042]

INDUSTRIAL APPLICABILITY The water-dispersible resin composition for rust-preventive paints of the present invention can be used not only for the primer but also for all paints which are directly coated on metal, and has excellent anti-rust property, water resistance and adhesion property to metal. It is excellent and useful as a vehicle for pollution-free water-based rust preventive paints.

Claims (3)

[Claims] 1. A compound represented by the general formula (1): [Wherein R is a hydrogen atom or a methyl group, A and B are alkyl groups having 1 to 10 carbon atoms which may have a substituent, m
And n represent a number from 0 to 100. ] The water dispersible resin composition for rust-preventive coatings which is a water dispersible composition of the polymer which contains the monomer shown by these at least 0.1weight%. 2. Monomers 1 to 80 represented by the general formula (1)
%, And one or two of monomers consisting of at least styrene and alkyl (meth) acrylate
The water-dispersible resin composition for rust-preventive paints according to claim 1, which is a water-dispersible resin composition of a copolymer with 99 to 20% by weight of one or more copolymerizable monomers. 3. Monomers 1 to 80 represented by the general formula (1)
% By weight, and 100 parts by weight of a mixed monomer comprising 99 to 20% by weight of at least one or two or more copolymerizable monomers of styrene and (meth) acrylic acid alkyl ester monomer, and a surfactant 0 0.001 to 5 parts by weight, water 3
A method for producing a water-dispersible resin composition for an anticorrosion paint, which comprises carrying out emulsion polymerization of 0 to 80 parts by weight together with a water-soluble polymerization initiator.